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    <title>Document</title>
    <style>
        .blue{
            color: blue;
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        .blue.big{
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        .blue.box{
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        .blue.box-1{
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    <div class="blue">
        这是一个div
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    <h1 class="blue big">麦麦真美丽</h1>

    <p class="blue box">这是p标签 -1</p>
    <p class="blue box-1">这是p标签 -2</p>
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